Durable goods orders slumped 7.3 percent in July, according to the Commerce Department, recording their biggest drop in nearly a year and snapping three straight months of gains. Economists polled by Reuters had expected durable goods orders to fall 4 percent.

Other key data due this week are the second reading of second-quarter gross domestic product (GDP) on Thursday.

Deal news took the early focus, with a big merger in the pharmaceutical industry.

Amgen said it will buy cancer drug maker Onyx Pharmaceuticals in a deal worth about $10.4 billion. The deal would mark the fifth-largest biotech acquisition ever. Shares of companies jumped.

Meanwhile, BATS Global Markets and Direct Edge said they would merge in a deal that would create the second-largest U.S. stock exchange. Financial terms of the transaction were not immediately announced. the deal is expected to close in the first half of 2014.

On Friday, the Dow Jones Industrial Average recaptured and closed above the psychologically-important 15,000 level, while the S&P 500 and Nasdaq also ended higher. Still, the Dow posted its third consecutive weekly decline

In Asia, China stocks outperformed other equity markets on Monday on economic optimism following economic data out of the U.S. on Friday. The Shanghai Composite rose to a one-week high, South Korea's Kospi hit a three-day high, Australian equities were steady around 5,137 points but Japan's Nikkei bucked the trend to dip 0.2 percent.

Meanwhile in Europe, shares were mixed in morning trade, while the U.K.'s FTSE 100 was closed for a public holiday. Dutch telecoms group KPN on Monday announced improved terms for the sale of its German business to Spanish telecom firm Telefonica, and shares in both companies rose on the news.